Automatic document feeder

ABSTRACT

The invention is an automatic document feeder (ADF) that includes an opening for feeding paper. The automatic document feeder is used for feeding papers from a paper holder through the opening in the feed direction. The automatic document feeder includes at least an inert-wheel holder, an inert wheel, a transmission shaft, a rolling wheel, and a paper-wiping element. The inert-wheel holder is installed at the opening and includes a holding shaft, an inert-wheel trough, and a paper-wiping trough, where the holding shaft is vertical to the feed direction. The inert wheel, which is installed in the inert-wheel trough, is capable of rolling in the direction of the holding shaft, and the inert wheel has an inert-wheel surface projecting off the inert-wheel trough. The transmission shaft is capable of rolling in the direction of the holding shaft. The rolling wheel is installed on the transmission shaft coaxially, and the rolling wheel has a rolling-wheel surface in contact with the inert-wheel surface. The paper-wiping element is installed on the transmission shaft with a position corresponding to the paper-wiping trough.

[0001] This application incorporates by reference Taiwan application Serial No. 091120221, filed Sep. 4, 2000.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The invention relates in general to an automatic document feeder (ADF), and more particularly to an automatic document feeder, which is used in a scanner.

[0004] 2. Description of the Related Art

[0005] A scanner with an automatic document feeder is an essential device in various PC peripheries. An automatic document feeder can effectively feed papers to be scanned into and out of a flatbed in the scanner and also make the scanner process document scans more quickly.

[0006] Referring to FIG. 1, a schematic view of a conventional automatic document feeder is shown. The conventional automatic document feeder 100 includes an opening for feeding papers (not shown in FIG. 1). The automatic document feeder 100 is used to feed papers placed on a paper holder (not shown in FIG. 1) out the opening and in the feed direction D.

[0007] The automatic document feeder 100 includes an inert-wheel holder 110, an inert wheel 120, a transmission shaft 130, and a rolling wheel 140. The inert-wheel holder 110 further includes a holding shaft 150 and an inert-wheel trough 160, where the holding shaft 150 is vertical to the feed direction D of the feed paper.

[0008] The inert-wheel holder 110 is installed at the opening to feed papers into the automatic document feeder 100. The inert wheel 120, installed in the inert-wheel trough 160, can roll in the direction of the holding shaft 150, and the inert-wheel surface 170 of the inert wheel 120 projects off the inert-wheel trough 160. The transmission shaft 130 rolls in the direction of the holding shaft 150. In addition, the rolling wheel 140 is fixed on the transmission shaft 130 coaxially, and the inert-wheel surface 170 is in contact with the rolling-wheel surface 180 of the rolling wheel 140.

[0009] The transmission shaft 130 transmits power to drive the rolling wheel 140 in the direction shown in FIG. 1. The rolling-wheel surface 180 thus applies a first force F1 on the inert-wheel surface 170, which drives the inert wheel 120 in the opposite direction of the rolling wheel 140 thereby feeding papers into the opening between the rolling wheel 140 and the inert wheel 120 in the feed direction D.

[0010] The paper holder can be a flatbed of a scanner, and the rolling wheel 140 and inert wheel 120 can be made of a flexible material with a rough surface, such as rubber.

[0011] As mentioned above, the conventional automatic document feeder has the following disadvantages: if the friction force between the feed paper and the inert-wheel holder 110 is greater than the total force applied to the feed paper by the wheel surface 180 and the inert-wheel surface 170 in the feed direction D, the feed paper will become jammed in the opening and cannot be released from the automatic document feeder 100, thereby negatively influencing the scanning process.

SUMMARY OF THE INVENTION

[0012] It is therefore an objective of the invention to provide an automatic document feeder in which the friction between the feed paper and the inert-wheel surface can be reduced so that feed papers can be fed out of the feeder easily and the scanning process can be smooth and uninterrupted.

[0013] The invention achieves the above-identified objective by providing an automatic document feeder. The automatic document feeder includes an opening for feeding papers into the scanner. The automatic document feeder is used to feed papers from the paper holder through the opening in the feed direction. The automatic document feeder includes at least an inert-wheel holder, an inert wheel, a transmission shaft, a rolling wheel, and a paper-wiping element. The inert-wheel holder is installed at the opening and includes a holding shaft, an inert-wheel shaft, and a paper-wiping trough, where the holding shaft is vertical to the feed direction. Additionally, the inert wheel is installed in the inert-wheel trough and can roll in the direction of the holding shaft, and the inert-wheel surface projects off the inert-wheel trough. The transmission shaft can roll in the direction of the holding shaft. The rolling wheel is installed on the transmission shaft coaxially and the rolling-wheel surface is in contact with the inert-wheel surface. The paper-wiping element is installed on the transmission shaft with a position corresponding to the paper-wiping trough. The transmission shaft drives the rolling wheel and the paper-wiping element. The rolling wheel, as driven by the transmission shaft, will apply a first force on the inert wheel causing it to roll in the opposite direction of the rolling wheel, thus feeding paper into the opening between the rolling wheel and the inert wheel in the feed direction. The paper-wiping element, as driven by the transmission shaft, can apply a second force to the feed paper, where the direction of the second force is parallel to the feed direction. The paper holder can be a flatbed of a scanner, and the paper-wiping element can be made of a flexible film, for example, mylar.

[0014] Other objectives, features, and advantages of the invention will become apparent from the following detailed description of the preferred but non-limiting embodiments. The following description is made with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 (Prior Art) is a schematic view of a conventional automatic document feeder; and

[0016]FIG. 2 illustrates a schematic view of an automatic document feeder according to a preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0017] The automatic document feeder in the invention is designed to include a paper-wiping element on the transmission shaft and a corresponding paper-wiping trough on the inert-wheel holder of a conventional automatic document feeder (so that the paper-wiping element can slightly touch or not touch the inert-wheel holder as it rolls with the transmission shaft). The function of the paper-wiping element is to apply a second force to the feed paper in the feed direction in order to make up for the insufficient force applied to the feed paper by the rolling wheel and the inert wheel alone. With the help of the paper-wiping element, the feed paper can overcome friction with the inert-wheel holder and pass through the paper feed path more smoothly. Therefore, the paper feed opening will not become jammed, and the overall scanning quality can be improved.

[0018] Referring to FIG. 2, a schematic view of an automatic document feeder according to a preferred embodiment of the invention is shown. The automatic document feeder 200 includes a paper-wiping element 210 and a paper-wiping trough 220 on the inert-wheel holder 110, in addition to the original components of the conventional automatic document feeder 100 shown in FIG. 1.

[0019] The paper-wiping element 210 is installed on the transmission shaft 130 with a position corresponding to the paper-wiping trough 220.

[0020] The transmission shaft 130 rolls in the direction shown in FIG. 2 and drives the rolling wheel 140 and the paper-wiping element 210. FIG. 1 shows that when the rolling wheel 140 rolls, it applies a first force F1 on the inert wheel 120, which rolls in the opposite direction of the rolling wheel 140. As a result, the feed paper can be fed into the opening between the rolling wheel 140 and inert wheel 120 in the feed direction D. The total force in the feed direction D, applied to the feed paper by the rolling wheel 140 and the inert wheel 120, is provided to feed papers out of the paper holder (not shown in FIG. 2).

[0021] However, in the typical automatic document feeder 100, in spite of the total force applied to the feed paper by the rolling wheel and the inert wheel, the total force in the feed direction D can be smaller than the friction between the feed paper and the inert-wheel holder 110. In this case, the feed paper will not be fed out of the feeder, and this can result in a paper jam.

[0022] The paper-wiping element 210 in the invention, which is absent in the conventional automatic document feeder 100, applies a second force F2 to the feed paper in the feed direction D. The second force F2 added up to the force originally applied by the rolling-wheel surface 180 and the inert-wheel surface 170 will overcome the friction force between the feed paper and the inert-wheel holder 100. As a result, the feed paper can be fed out of the automatic document feeder 200 smoothly, preventing a paper jam.

[0023] The paper-wiping trough 220 is designed for the flexible paper-wiping element 210 to roll through the inert-wheel holder 110 with little or no contact with the inert-wheel holder 110. The greatest second force F2 applied to the feed paper by the paper-wiping element 210 is generated when the second force F2 is applied to the fringe of the feed paper parallel to the holding shaft 150.

[0024] The paper holder as mentioned above can be a flatbed of a scanner. The paper-wiping element 210 can be made of a flexible film, such as mylar.

[0025] The paper-wiping element 210, when added to the transmission shaft 130, can roll with the transmission shaft 130 and apply a second force F2 to the feed paper. Therefore, the feed paper will not become jammed in the automatic document feeder due to insufficient total force in the feed direction D applied to the feed paper by the rolling-wheel surface 180 and the inert-wheel surface 170.

[0026] The automatic document feeder according to the preferred embodiment of the invention has at least the following advantages: even if the friction force between the feed paper and the inert-wheel holder is great enough to block the paper feed, the paper-wiping element added on the automatic document feeder in the invention will apply a second force to the feed paper, which results in a greater total force to the feed paper in the feed direction than the conventional type so that the feed paper can be fed out of the paper holder smoothly. Therefore, paper jams, which occur frequently in conventional automatic document feeders, can be eliminated, and the scanning process can continue smoothly.

[0027] While the invention has been described by way of example and in terms of a preferred embodiment, it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures. 

What is claimed is:
 1. An automatic document feeder (ADF), comprising an opening for feeding papers, the automatic document feeder feeding papers from a paper holder through the opening in a feed direction, the automatic document feeder comprising at least: an inert-wheel holder, installed at the opening, the inert-wheel holder comprising a holding shaft, an inert-wheel trough, and a paper-wiping trough, wherein the holding shaft is vertical to the feed direction; an inert wheel, installed in the inert-wheel trough, capable of rolling in the direction of the holding shaft, the inert wheel having an inert-wheel surface projecting off the inert-wheel trough; a transmission shaft, capable of rolling in the direction of the holding shaft; a rolling wheel, installed on the transmission shaft coaxially, the rolling wheel having a rolling-wheel surface in contact with the inert-wheel surface; and a paper-wiping element, installed on the transmission shaft with a position corresponding to the paper-wiping trough; wherein the transmission shaft drives the rolling wheel and causes the paper-wiping element to roll; the rolling wheel, as driven, applies a first force to the inert wheel to roll in an opposite direction of the rolling wheel, thereby feeding papers into the opening between the rolling wheel and the inert wheel in the feed direction, and the paper-wiping element, as driven, applies a second force to the feed paper, which is parallel to the feed direction.
 2. The automatic document feeder according to claim 1, wherein the paper holder is a flatbed of a scanner.
 3. The automatic document feeder according to claim 1, wherein the paper-wiping element is made of a flexible film.
 4. The automatic document feeder according to claim 3, wherein the film is mylar.
 5. The automatic document feeder according to claim 4, wherein the paper holder is a flatbed of a scanner.
 6. A scanner, comprising an automatic document feeder, the automatic document feeder comprising an opening for feeding papers, the automatic document feeder feeding papers from a paper holder through an opening in a feed direction, the scanner comprising at least: an inert-wheel holder, installed at the opening, the inert-wheel holder comprising a holding shaft, an inert-wheel trough, and a paper-wiping trough, wherein the holding shaft is vertical to the feed direction; an inert wheel, installed in the inert-wheel trough, capable of rolling in the direction of the holding shaft, the inert wheel having an inert-wheel surface projecting off the inert-wheel trough; a transmission shaft, capable of rolling in the direction of the holding shaft; a rolling wheel, installed on the transmission shaft coaxially, the rolling wheel having a rolling-wheel surface in contact with the inert-wheel surface; and a paper-wiping element, installed on the transmission shaft with a position corresponding to the paper-wiping trough; wherein the transmission shaft drives the rolling wheel and causes the paper-wiping element to roll; the rolling wheel, as driven, applies a first force on the inert wheel to roll in an opposite direction of the rolling wheel, thereby feeding the feed papers into the opening between the rolling wheel and the inert wheel in the feed direction; and the paper-wiping element, as driven, applies a second force to the feed paper, which is parallel to the feed direction.
 7. The automatic document feeder according to claim 6, wherein the paper-wiping element is made of a flexible film.
 8. The automatic document feeder according to claim 7, wherein the film is mylar. 